CAREER: High-Resolution Hybrid Printing of Wearable Heaters with Shape-Changeable Structures

四维(4D)打印是一种新兴的添加剂制造技术，它使三维(3D)打印结构在受到特定刺激时能够在预定义的形状之间变形。目前，各种3D打印方法被广泛用于制造形状变化的对象。然而，这些工艺中的大多数要么复杂、成本高昂、适用材料有限，要么分辨率低，不适合生产高精度的多材料结构。为了应对这一挑战，学院早期职业发展计划(CALEAR)项目支持与高分辨率混合4D打印相关的新知识的研究，其中两种类型的打印工艺用于材料沉积，并将创建制造具有精确变形的高分辨率多材料形状变化结构的新方法。基础研究可以加快这些4D打印系统和工艺的发展，这可能导致在航空航天、医疗保健、生物和汽车行业的潜在应用，对美国经济、国民健康和社会产生潜在影响。该项目的教育目标是通过激励少数族裔和代表不足的群体的学生，吸引更多的本科生进入先进制造业领域，培养研究生，并为K-12学生提供动手研究和演示机会，来改善STEM教育。这个职业项目将专注于开发一种混合4D打印工艺，它集成了高分辨率电液动力(EHD)打印和高通量挤压打印，以制造具有变形能力的柔性结构。如果成功，该项目将极大地促进对材料与印刷过程之间复杂相互作用的科学理解，包括1)了解挤压印刷结构如何影响EHD印刷过程，以及EHD沉积的飞行速度如何影响印刷变形基板的分辨率和冲击损伤；2)研究EHD印刷电压和印刷床温如何影响用选定的变形材料印刷的结构的变形能力、灵活性和机械强度；以及3)了解多材料结构的变形机理，并开发和评估可变形状柔性结构的可行设计。在大学前的外展计划(叛逆研究学者、工程暑期学院和密歇根大学的发现工程)和其他教育活动中，该项目将为从K-12到研究生水平的学生提供课程材料、学习模块和动手实验项目。计划中的多学科研究和以教学为基础的教育和推广计划将把研究成果和学生的活动联系起来，目标是提高他们对先进制造的兴趣和现代工业的需求。该项目由先进制造计划和既定的激励竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Four-dimensional (4D) printing is an emerging additive manufacturing technology that enables three-dimensional (3D) printed structures to deform between predefined shapes when exposed to certain stimuli. Currently, various 3D printing approaches are widely used to produce shape-changing objects. However, most of these processes are either complex, costly, have limited applicable materials, or offer low resolution, making them unsuitable for producing high-precision multi-material structures. To address this challenge, this Faculty Early Career Development Program (CAREER) project supports research that will build new knowledge related to high-resolution hybrid 4D printing, in which two types of printing processes are used for material deposition, and will create new methods of fabricating high-resolution multi-material shape-changing structures with precise deformations. The fundamental research could speed the development of these 4D printing systems and processes, which can lead to potential applications in aerospace, healthcare, biology, and automotive industries, with potential impact on the US economy, national health, and society. The educational objective of the project is to improve STEM education by inspiring students from minority and underrepresented groups, attracting more undergraduate students to the advanced manufacturing field, training graduate students, and providing hands-on research and demonstration opportunities to K-12 students.This CAREER project will focus on developing a hybrid 4D printing process, which integrates high-resolution electrohydrodynamic (EHD) printing and high-throughput extrusion printing to fabricate flexible structures with shape-changing capability. If successful, this project will significantly advance the scientific understanding of the complex interactions between materials and printing processes, including 1) understanding how the extrusion-printed structures affect the EHD printing process and how the in-flight speed of EHD deposition affects the resolution and impact damage on the printed shape-changing substrate; 2) studying how EHD printing voltage and printing bed temperature affect deformation capability, flexibility, and mechanical strength of structures printed with selected shape-changing materials; and 3) understanding the shape-changing mechanism for multi-material structures, and developing and evaluating feasible designs for shape-changeable flexible structures. In pre-college outreach programs (Rebel Research Scholars, Engineering Summer Academy, and Discover Engineering at UM) and other educational activities, this project will provide course materials, learning modules, and hands-on lab projects for students from K-12 to graduate level. The planned multidisciplinary research- and teaching-based education and outreach programs will link the research outcomes and students’ activities, with a goal of increasing their interest in advanced manufacturing and the needs of modern industries.This project is jointly funded by the Advanced Manufacturing program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.